Mining machine sensing signal transmission connection

ABSTRACT

A mineral mining machine having a rotary cutter and a probe on the cutter head which senses the cutting horizon of the cutter head relative to boundaries of the mineral seam and which derives an electric signal which is fed to control means on the body of the machine for controlling the machine&#39;&#39;s steering mechanism. The signal is conveyed from the rotating cutter to the non-rotating body via two spaced annular plates arranged as a capacitor.

United States Patent 11-91 Hartley et al. v

1451 Nov. 13, 1973 MINING MACHINE SENSING SIGNAL TRANSMISSION CONNECTIONInventors: Dennis Hartley; Derek Alford;

Norman Albert Plumpton, all of Burton-on-Trent, England Assignee: CoalIndustry (Patents) Limited,

London, England Filed: Dec. 7, 1971 Appl. No.: 205,694

us. Cl. 299/1, 339/5 R 1m. 01. E21c 35/24, HQ 1r 39/56 Field of Search299/1; 339/5 R, 5 P,

References Cited UNITED STATES PATENTS Addison 299/1 Wachsman 339/5 PSnodgrass et al. 339/8 R Primary Examiner-Ernest R. PurserAttorney-Richard K. Stevens et a] [57] ABSTRACT .A mineral miningmachine having a rotary cutter and a probe on the cutterhead whichsenses the cutting horizon of the cutter head relative to boundaries ofthe mineral seam and which derives an electric signal which is fed tocontrol means on the body of the machine for controlling the machinessteering mechanism. The signal is conveyed from the rotating cutter tothe nonerotating body via two spaced annular plates arranged as acapacitor.

8 Claims, 2 Drawing Figures MINING MACHINE SENSING SIGNAL TRANSMISSIONCONNECTION This invention relates to mineral mining machines and inparticular to mining machines of the kind comprising rotary cutters fromwhich it is necessary to conduct electric signals, for example a machinehaving means on the cutter which are sensitive to the mineral being cutby the cutter and which produce a signal indicative of the mineral beingcut, the signal being conducted to the steering mechanism of themachine.

With known mining machines of this kind slip-rings were used to conductthe signal from the rotary cutter to the body of the machine.Unfortunately, such a technique was found to be unreliable, and liableto be affected by mineral particles which penetrated into the slip-ringchamber. Such a technique also suffered from the effect of electricalnoise interference which tended to mask out any change in the signal dueto a change in the mineral being cut by the cutter.

An object of the present invention is to provide a mining machinecomprising improved means for conducting an electrical signal from therotary cutter to the body of the machine.

According to the present invention a mineral mining machine comprises abody, a rotary drive shaft extending from the body, a rotary cuttermounted on the shaft, means sensitive to a characteristic featureexisting adjacent to the cutter and adapted to produce an electricsignal indicative of the feature, and first and second electricallyconductive annular elements coaxial with the drive shaft and Spacedfrom, but adjacent to, each other, the first element being in electricalcontact with the means and mounted for rotation with, but electricallyinsulated from, the cutter, the second element being mounted on, butelectrically insulated from, the machine body and being in electricalcontact with receiver-means adapted to receive electric signals.

Advantageously, the said first and second elements are located within apacked annular chamber the sides of which are formed partly by a rotaryhousing member secured to the cutter and partly by a stationary housingmember-secured to the machine body.

Preferably the annular chamber is packed with an epoxy resin.Alternatively, the annular chamber may be packed with grease.

Preferably, the radially outer portions of the two housing members forma labyrinth.

An annular resiliently urged seal may be located so as to act betweenthe two housing members.

Preferably, the said means are sensitive to the cutting horizon of thecutter and the receiver means are control means adapted to control thesteering mechanism of the machine.

By way of example only, one embodiment of the invention will now bedescribed with reference to the accompanying drawings in which i FIG. 1is a diagrammatic sectional view along a drive shaft of a mining machineconstructed in accordance with the present invention;

FIG. 2 is an incomplete diagrammatic sectional view along line II--Il ofFIG. 1.

Referring to the drawings which show a part of a mining machine adjacentto the cutting end of the machine and in particular the part where therotary cutting unit 2 is attached to the non-rotary body 4. The cuttingunit 2 comprises a rotary drive shaft 6 and a cutter drum 8 drivablymounted onto the shaft 6.

The cutter drum 8 is provided with means 9 sensitive to the cuttinghorizon of the cutter drum 8, which comprise a flexibly mounted cuttertool 11 the vibrational movement of which with respect to its mountingdepends upon the hardness of mineral momentarily being cut by therotating tool, and a device which is sensitive to such movement andwhich produce an electrical signal having a frequency indicative of themovement. The signal is fed from the device along a cable (not shown)housed within passages 10 (only one of which is shown) provided on thedrum 8, and a passage 12 provided in a rotary housing member 14 securedto the drum 8by bolts 15. The cable is connected to a terminal 16rigidly attached to an annular plate18 which is secured to a ring 20 ofelectrically insulating material bolted by recessed bolts 22 to thehousing member 14, the plate 18 being arranged co-axial with the driveshaft 6.

A second annular plate 24 is mounted adjacent to, but spaced from, theplate 18 and is secured to a ring 26 of electrically insulating materialbolted by recessed bolts 28 to a stationary housing member 30 which isbolted by bolts 32 to the machine body 4. A cable (-not shown) isconnected to a terminal 34 rigidly attached to the plate 24 and extendsalong a passage 36 in the housing member 30 and the casing of themachine body 4 to receiver means 37 adapted to receive the electricsignals and to feed the signals to control means (not shown) whichcontrol the steering mechanism of the machine.

The rotary and stationary housing members 14, 30 form an annular chamber38 having two portions 39, 41 within which are housed the plates 18 and24, respectively, and which are packed with a suitable nonelectricallyconductive material, as for example an epoxy resin or grease which tendsto prevent moisture and particles of mineral entering the chamber 38.

In the case of the chamber 38 being packed with epoxy resin, the housingmembers 14, 30 are laid on the ground with their respective chamberportions 39, 41 uppermost. Next the plates 18, 24 arellocated inposition within the chamber portions '39, 41, respectively, and thecables connected to the terminals, 16, 34 and passed along the passages12, 36 which are then plugged by resilient stoppers. Molten epoxy resinis then poured into the chamber portions 39, 41 until the portions arefull with the plates 18, 24 completely covered by the resin which isthen allowed to set. When the epoxy resin is set the housing members 14,30 are assembled and connected to the cutter drum 8 and the body of themachine, respectively, with the two exposed faces of the epoxy resinadjacent to each other. A thin layer of grease may be provided betweenthe two faces of the epoxy resin. In addition before the epoxy resin ispoured into the chamber portions 39, 41 the inside walls of the portionsmay be sprayed with a nonelectrically conductive varnish which ensuresthat during any subsequent operation of the machine, if any water shouldenter the chamber 38 it cannot cause an electrical short circuit.

1 The radially outer portions of the two housing members 14, 30 form alabyrinth which assists in preventing particles of mineral entering thechamber 38.

Two resiliently loaded annular seals 40, 42 are located in groovesformed in the rotary housing member l4, and arranged to act between thetwo housing members 14, 30. Each seal 40, 42 comprises a nylon pad 44which is urged towards the stationary housing member 30 by a spring 46,the force of which can be adjusted by screw adjustments 48.

In alternative arrangements of the invention one or both of the seals40, 42 are dispensed with.

Grease nipples 50 are provided for feeding grease into the labyrinth.

In operation the electrical signal which has a frequency proportional tothe hardness of the mineral being cut by the cutting drum 8 is fed fromthe previously mentioned means 9 to the annular plate 18 via theterminal 16. The two annular plates 18, 24 form a capacitor coupling andan electrical signal having a lower amplitude, but the same frequency asthe signal fed to the plate 18 is conducted from the plate 24 via theterminal 34 to the receiver means 37 an in turn to the control means.

Upon the cutter drum cutting a mineral of differing hardness, thefrequency of the signal fed to the plate 18 and consequently of thatconducted from the plate 24, is changed by a proportional amount. Thusthe control means is informed of the change in cutting horizon of thecutter drum 8 and the steering mechanism is actuated to suitably steerthe machine and adjust the cuttin horizon.

Typical spacing of the plates 18, 24 is betwee 1/ The invention providesa means of conducting electrical signals from the rotating cutter unit 2to the body 4 of the machine which is reliable, robust and relativelyfree from electrical noise. Thus any change in signal due to change inthe cutting horizon of the cutter and hardness of mineral being cut canbe easily recorded.

The invention can be also used with other sensitive means mounted on therotary cutter unit which produce an electric signal, for example withnucleonic probes mounted on the unit and arranged to detect the boundaryof a mineral adjacent to the cutter unit, or a probe sensitive to thegaseous atmosphere around the cutter unit.

We claim:

1. A mineral mining machine comprising a body, a rotary drive shaftextending from the body, a rotary cutter mounted on the shaft, meanssensitive to a characteristic feature existing adjacent to the cutterand adapted to produce an electric signal indicative of the feature,receiver means mounted on the body and adapted to receive electricsignals, and first and second electrically conductive annular elementsco-axial with the drive shaft and spaced from, but adjacent to, eachother, the first element being in electrical contact eith the means andmounted for rotation with, but electrically insulated from, the cutter,the second element being mounted on, but electrically insulated from,the machine body being in electrical contact with the receiver means.

2. A machine as claimed in claim 1, comprising two housing members whichform a housing within which the first and second elements are located,one of the housing members being secured to the cutter and the otherhousing member being secured to the machine body.

3. A machine as claimed in claim 2, in which the housing is packed withan epoxy resin.

4. A machine as claimed in claim2, in with the housing is packed withgrease.

5. A mineral mining machine comprising a body, a rotary drive shaftextending from the body, a rotary cutter mounted on the shaft, meanssensitive to the cutting horizon of the cutter relative to the mineralseam and adapted to produce an electric signal indicative of the cuttinghorizon, receiver means mounted on the body and adapted to receive theelectric signals, first and second electrically conductive annularelements co-axial with the drive shaft and spaced from, but adjacent to,each other, the first element being in electrical contact with the meansand mounted for rotation with, but electrically insulated from, thecutter, the second element being mounted on, but electrically insulatedfrom, the mahcine body and being in electrical contact with the receivermeans, and two housing members which form a housing within which thefirst and second elements are located, one of the housing members beingsecured to the cutter and the other housing member being secured to themachine body.

6. A machine as claimed in claim 5, in which the housing is packed witha non-electrically conductive material.

7. A machine as claimed in claim 5, in which the radially outer portionsof the two housing members form a labyrinth.

8. A machine as claimed in claim 6, in which at least one resilientlyurged seal is located so as to act between the two housing members.

1. A mineral mining machine comprising a body, a rotary drive shaftextending from the body, a rotary cutter mounted on the shaft, meanssensitive to a characteristic feature existing adjacent to the cutterand adapted to produce an electric signal indicative of the feature,receiver means mounted on the body and adapted to receive electricsignals, and first and second electrically conductive annular elementsco-axial with the drive shaft and spaced from, but adjacent to, eachother, the first element being in electrical contact eith the means andmounted for rotation with, but electrically insulated from, the cutter,the second element being mounted on, but electrically insulated from,the machine body being in electrical contact with the receiver means. 2.A machine as claimed in claim 1, comprising two housing members whichform a housing within which the first and second elements are located,one of the housing members being secured to the cutter and the otherhousing member being secured to the machine body.
 3. A machine asclaimed in claim 2, in which the housing is packed with an epoxy resin.4. A machine as claimed in claim 2, in with the housing is packed withgrease.
 5. A mineral mining machine comprising a body, a rotary driveshaft extending from the body, a rotary cutter mounted on the shaft,means sensitive to the cutting horizon of the cutter relative to themineral seam and adapted to produce an electric signal indicative of thecutting horizon, receiver means mounted on the body and adapted toreceive the electric signals, first and second electrically conductiveannular elements co-axial with the drive shaft and spaced from, butadjacent to, each other, the first element being in electrical contactwith the means and mounted for rotation with, but electrically insulatedfrom, the cutter, the second element being mounted on, but electricallyinsulated from, the mahcine body and being in electrical contact withthe receiver means, and two housing members which form a housing withinwhich the first and second elements are located, one of the housingmembers being secured to the cutter and the other housing member beingsecured to the machine body.
 6. A machine as claimed in claim 5, inwhich the hoUsing is packed with a non-electrically conductive material.7. A machine as claimed in claim 5, in which the radially outer portionsof the two housing members form a labyrinth.
 8. A machine as claimed inclaim 6, in which at least one resiliently urged seal is located so asto act between the two housing members.